ABSTRACT Alcohol use disorder (AUD) onset peaks during young adulthood. Young adults report more frequent, heavier alcohol use than older adults and experience substantial negative consequences (e.g., accidental injury) and risk of developing a chronic AUD. Current young adult alcohol intervention strategies, however, have modest effects. To address this gap, we propose to develop a novel, mobile sleep intervention for heavy-drinking young adults. Sleep may be a useful treatment target for this population for several reasons. Poor sleep is common among young adults who drink heavily and an AUD risk factor. Young adults are also interested in information to help them sleep better. Further, as a standard practice, behavioral sleep interventions address alcohol use and may provide a gateway for intervening on alcohol use. We conducted a preliminary test of a mobile sleep intervention in 42 heavy-drinking young adults. The primary components were: (1) brief, web- based sleep hygiene advice including the standard advice to moderate drinking for better sleep and (2) daily web-based sleep and alcohol self-monitoring plus wearing a sleep/wake activity tracker daily. Our results demonstrated promising effects on drinking and sleep. The next phase of intervention development involves testing our intervention components compared to matched control conditions and whether a new component suggested by participants in post-treatment interviews further improves outcomes. Specifically, participants indicated a preference for personalized feedback about their sleep diary and tracker data and the connections with alcohol use. Additionally, exciting new alcohol biosensor technology has emerged that allows continuous tracking of blood alcohol level and provides an objective measure of participant alcohol consumption. Through this technology we can provide personalized alcohol-sleep interaction feedback using both objective sleep/alcohol trackers and sleep/alcohol diary data. The current proposal will develop and test a mobile sleep/alcohol self-monitoring + sleep/alcohol data feedback intervention in 120 heavy-drinking young adults. All participants will wear sleep and alcohol trackers daily. The primary intervention will include: (1) web-based sleep hygiene advice + sleep/alcohol diary self-monitoring + sleep/alcohol data feedback. This condition (n=60) will be compared to the matched control conditions that only include these components: (1) web-based sleep hygiene advice (n=30) or (2) web-based sleep hygiene advice + sleep/alcohol diary self-monitoring (n=30). The primary objective is to evaluate sleep intervention component feasibility, acceptability, and preliminary efficacy on alcohol outcomes to inform a Stage II randomized trial comparing the final sleep intervention with a standard alcohol intervention. This study is in line with NIAAA?s strategic interest to identify novel targets to improve alcohol prevention and intervention efforts for young people. Ultimately, this research could result in an efficacious, low-cost intervention that has broad population reach through the use of technology and a substantial public health impact by reducing AUD risk at a crucial developmental stage.